Is a Vaughan address in a regulated flood area, and whose map says so?

The Toronto and Region Conservation Authority's jurisdiction takes in nine watersheds, among them the Humber River, the Don River and the Rouge River, and its own table puts 100% of Vaughan's population inside it; the Lake Simcoe Region authority's list of the municipalities in its jurisdiction doesn't name Vaughan. The authority's Regulated Area Search takes an address or postal code and says whether a property falls inside the area regulated under Ontario Regulation 41/24, where development could be subject to flooding, erosion or dynamic beaches, along with wetlands, shorelines and watercourses. The authority says not all regulated areas may be mapped, and that a hazard doesn't have to be mapped to be regulated.

A permit from the authority is needed before any new development activity in its regulated area, such as building a new home, and the authority says the municipality cannot legally issue a building permit until its permit or clearance has been obtained, so it doesn't replace the City's building permit. A regulated-area result governs permits for work near water, such as additions, decks and grading; it is not a forecast that a home will flood, and a home outside the mapped area can still take water through a basement. Under the Conservation Authorities Act as amended in 2026, the Toronto and Region authority is to join the Central Lake Ontario Regional Conservation Authority on 1 February 2027 or a later date set by regulation.

• TRCA Regulated Area Search: the address search for the Toronto and Region Conservation Authority's regulated area
• About TRCA: jurisdiction: the authority's watersheds and the share of each municipality's population inside them
• TRCA: building a new home: the authority's permit and the municipality's building permit
• LSRCA: planning: the Lake Simcoe Region authority's municipalities and its permits under Ontario Regulation 41/24
• Bill 97, Plan to Protect Ontario Act (Budget Measures), 2026: Schedule 3 amends the Conservation Authorities Act; the transition date is 1 February 2027 or a later date set by regulation
• Regional conservation authority boundaries (ERO 025-1257): the Province's decision of 10 March 2026 on which authority joins which of the nine regional authorities
• Ontario Regulation 41/24: Prohibited Activities, Exemptions and Permits, the regulation behind every conservation authority's regulated area

Conservation-authority regulated-area and flood plain checks are not currently included in our reports, so for a Vaughan home the authority's own map is the place to look. The full report's water and flooding group does cover past floods seen by satellite, nearby creeks, rivers and ponds, and mapped wetlands for any Vaughan address.

What we cover, city by city See the sample report